What happens when you match to tree?

What happens when you match to tree?

I encountered a tree that was stunning! IF you link to just one person in a tree do you inherit every with it. This tree and had many links to other trees and some how the tree ended up with duplicate people there was 16 of the same individual and multiples every where. If you accept cousin match can you limit it to just that person? I really would like to understand what would cause such corruption. I would necessary want to inherit the entire line either. It was an amazing experience! Any ideas appreciated! Dawn